fix

Author: prasankh

ads/opctl/operator/lowcode/common/transformations.py

@@ -219,7 +219,7 @@ def _missing_value_imputation_add(self, df):
         -------
             A new Pandas DataFrame without missing values.
         """
-        df.fillna(0, inplace=True)
+        return df.fillna(0)
 
     def _outlier_treatment(self, df):
         """